code: def test_common_type_single_argument(self, xp, dtype):
      array = _generate_type_routines_input(xp, dtype, "array")
      ret = xp.common_type(array)
      assert type(ret) == type
      return ret
  
file_path: cupy/tests/cupy_tests/test_type_routines.py
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 2 for calling the TestCommonType obj's underlying member method code with example usage: obj.test_common_type_single_argument(xp, dtype) and returns: ret